Competition continued

Question 1

What are 3 factors that affect species distribution?

Answer 1

1. Dispersal ability
2. Adaptation
3. Competition

Question 2

Give an example of competition-mediated distribution.

Answer 2

T. latifolia thrives in shallow water. T. angustifolia can thrive in both shallow and deep water, but is not found in shallow water when T. latifolia is present due to competition.

Question 3

Define a Darwinian Demon.

Answer 3

A hypothetical organism that can maximise all fitness aspects simultaneously, i.e. it can optimise itself to any condition.

Question 4

A Darwinian Demon produces maximum offspring and lives indefinitely. True of false?

Answer 4

True.

Question 5

Darwinian Demons are real. True or false?

Answer 5

False.

Question 6

Trade-offs must occur in competition. This helps to establish niche boundaries, allowing organisms to…

Answer 6

Coexist.

Question 7

Give an example of a trade-off.

Answer 7

In plants, the first species to colonise are fast growing but very small. The last species to colonise are slow growing but larger. The trade-off is speed for size.

Question 8

Define intermediate disturbance.

Answer 8

When ecological disturbance is neither too rare nor too frequent.

Question 9

What effect does ecological disturbance have on local species diversity and why?

Answer 9

It maximises diversity. In low disturbance organisms are left to thrive, thus it selects for organisms that are the fittest. High levels of disturbance also only selects for the organisms that can withstand it. In both cases species are lost, intermediate disturbance strikes a balance.

Question 10

Give an example of how intermediate disturbance might work in a forest community.

Answer 10

If there is mid-level disturbance, for example a few trees fell over in a storm, light gaps would be created allowing pioneer species to thrive alongside taller plants.

Question 11

Define storage effect.

Answer 11

A mechanism that seeks to explain how a wide variety of similar species is able to coexist in one environment.

Question 12

Under storage effect, what must species endure in a) good years and b) bad years?

Answer 12

a) Intense competition

b) Unfavourable conditions

Question 13

Define apparent competition.

Answer 13

Indirect competition between 2 victim species that share a natural enemy.

Question 14

What causes apparent competition?

Answer 14

Numerical changes in the common enemy.

Question 15

Explain how apparent competition works. Use the hypothetical victims V1 and V2, and CE as common enemy.

Answer 15

1. V1’s food source increases
2. Because there is more V1 to eat. CE increases.
3. Because CE has increased, there are more of them around to eat V2, thus V2 decreases.

Question 16

Give a real life experiment that illustrates apparent competition.

Answer 16

1. Parasitoid wasps lay their eggs in 2 hosts, plodia and ephestia.
2. In monoculture plodia is able to withstand higher numbers of parasitoid wasp than ephestia
3. Both hosts were put in a box separated by mesh so they are not directly competing for resources. The wasps can move between the sections.
4. Ephestia went extinct due to apparent competition. Plodia remained in higher numbers, causing there to be more wasps, which then ate all the ephestia. Peak times.

Question 17

Gause’s Law is relevant to apparent competition. How?

Answer 17

It operates on a similar principle - the species that withstands predation better will dominate.